Method and an apparatus for cooling a computer

ABSTRACT

A heat exchanging system comprising circulating fluid through a tube coupled to an electronic component in a first part of a computing device and to a heat transfer plate in a second part of the computing device.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of co-pending U.S. patent applicationSer. No. 13/231,739, filed Sep. 13, 2011, which is a continuation ofco-pending U.S. patent application Ser. No. 12/372,660, filed Feb. 17,2009, issued as U.S. Pat. No. 8,016,023, which is a continuation ofco-pending U.S. patent application Ser. No. 11/395,900, filed Mar. 30,2006, issued as U.S. Pat. No. 7,490,656, and which is a continuation ofco-pending U.S. patent application Ser. No. 09/607,871, filed Jun. 30,2000, issued U.S. Pat. No. 7,086,452.

FIELD OF THE INVENTION

This invention relates to electronic devices and more particularly tothe dissipation of heat generated by a microprocessor.

BACKGROUND

In operation, microprocessors and other electronic devices generateheat. Excess heat can damage a device if it is not dissipated.Therefore, generally, microprocessors and other heat-generatingelectronic devices utilize heat dissipating structures to dissipateexcess heat.

FIG. 1 illustrates computer system 10 of the prior art. Microprocessor40 or other heat-generating electronic devices generally are affixed toa printed circuit board (“PCB”) 20 that is coupled to spreader plate 30.In the case of microprocessor 40, a heat exchange system is usuallyaffixed to the PCB through bolts or screws with an established gap orbond line thickness between a cooling plate or heat sink andmicroprocessor 40. Heat pipe 55 is coupled to heat exchanger 50 whichallows air to pass through air inlet 70 and exit air outlet 80. Fan 60generally continuously operates to cause air to pass through air inlet70 and out air outlet 80 in order to cool computer system 10. Onedisadvantage to a conventional computer system such as that shown inFIG. 1 is due to the size of heat exchanger 50 and the limitedcapability of the heat pipe 55 to move heat to small air cooled heatexchanger 50 to cool a heat-generating source such as the microprocessor40 that is shown in FIG. 1. What is needed is a configuration of acomputer system whereby the heat-generating source is cooled at anenhanced rate.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention. In the drawings,

FIG. 1 is a schematic angled view of a computer system of the prior art;

FIG. 2 illustrates a top angled view of a computer system in accordancewith one embodiment of the invention;

FIG. 3 illustrates the path of fluid flow when an external source offluid is used;

FIG. 4 illustrates a bi-directional tube coupled to an external chilledsource in accordance with one embodiment of the invention;

FIG. 5 illustrates a bi-directional tube coupled to an external chilledsource in accordance with one embodiment of the invention;

FIG. 6 illustrates a cross-sectional view of the first heat transferplate in accordance with one embodiment of the invention;

FIG. 7 illustrates a top view of the first heat transfer plate inaccordance with one embodiment of the invention;

FIG. 8 illustrates a top view of the second heat transfer plate inaccordance with one embodiment of the invention;

FIG. 9 illustrates a cross-sectional view of the second heat transferplate in accordance with one embodiment of the invention;

FIG. 10 illustrates a flow diagram in which fluid flows through a firstand a second part of computing device in accordance with one embodimentof the invention one embodiment of the invention; and

FIG. 11 illustrates a flow diagram in which chilled fluid is supplied tothe computing device.

DETAILED DESCRIPTION

The invention relates to a cooling system that improves the coolingcapacity of a computer system and thereby improves the computingperformance of the computer system. The computer system may include anotebook computer or other suitable portable computer systems. Thecomputer system comprises a tube that is coupled to a first heattransfer plate and to a heat-generating element. The tube contains afluid that removes heat from a heat source transferring it to a heattransfer plate. A second heat transfer plate is also used to transferthe waste heat from the cooling liquid to the ambient cooling air. Inaddition to cooling the computer system, techniques of the invention arealso able to reduce noise about in the range of 35 to 45 decibelscompared to conventional systems that use fans. An apparatusincorporating such a cooling system is described.

FIG. 2 illustrates an angled top side view of computer system 100 inaccordance with one embodiment of the invention. In FIG. 2,microprocessor 130 is mounted on a printed circuit board (“PCB”) (notshown). Tube 115 provides cooling fluid to heat transfer plate 125 (alsoreferred to herein as the first heat transfer plate). The fluid in tube115 includes any fluid that may be used for cooling. For instance, watermay be used. Water is the preferred fluid to use because water is easilyreplaceable when a portion of the water has dissipated and water causesless scaling in the heat transfer plate 125. Additionally, if the wateris accidentally released from computer system 100, there are noenvironmental regulations that are triggered for the clean up of wateras opposed to other fluids that may be regulated. Other fluids that maybe used in tube 115 include various oils, fluorinert which iscommercially available from 3M located in St. Paul, Minn., FC75,Coolanol 25, Coolanol 45, and liquid refrigerants.

Tube 115, may comprise rubber, plastic such as polyvinyl chloride,aluminum, copper, stainless steel or other suitable material.Preferably, tube 115 in second part 120 of computing device 100 iscomprised of metal such as stainless steel, aluminum, copper or anyother suitable metal. Tube 115 located in first part 110 and second part120 of computing device 100 may be made of the same or differentmaterial. In one embodiment, computer device 100 is a notebook orportable computer and first part 110 houses the motherboard, powersupply and the like (not shown) as is well known in the art and secondpart 120 houses a liquid crystal display (not shown) or the like. Tube115 has a diameter in the range of about 2 mm to 15 mm and a length thatranges from 500 mm to 5000 mm depending on the heat removal requirement.Tube 115 is secured to first part 110 and second part 120 of computersystem 100. There are a variety of ways that tube 115 may be secured tocomputer system 100. Mechanical means may be used such as welding orsoldering the tube to various heat spreaders and heat transfer plate, astand off and clamps, or clips that surround tube 115 and attach to thebase of computer system 110.

There are also numerous ways in which tube 115 may be arranged relativeto heat transfer plate 125 in first part 110 and heat transfer plate 210(also referred to herein as the second heat transfer plate) in secondpart 120 of computing system 100 to remove heat generated by computersystem 100 in the range of 10 watts to 50 watts. FIG. 2 illustrates onesuch arrangement. Tube 115 is coupled to fluid container 140 whichcontains the fluid that is pumped by pump 150 at a rate of about 1milliliter per second (“ml/sec”) to 10 ml/sec through tube 115. Fluidcontainer 140 generally has a volume that ranges from about 10 cubiccentimeters (“cm³”) to 25 cm³. The fluid contained within tube 115 mayrange from 25 ml to 250 ml. The thermal cooling capability is directlyproportional to the mass flow rate of the cooling medium removing heatfrom the heat generation source to a heat rejection point such as a heattransfer plate. As a result, the amount of fluid pumped through tube 115may increase or decrease the amount of cooling that occurs tomicroprocessor 130. One skilled in the art, therefore, may adjust themass flow rate by modifying the design parameters such as the length orthe diameter of tube 115 in order to increase or decrease the rate ofcooling.

Temperature sensor 180 is coupled to fluid container 140, pump 150, andto power management system 132. Temperature sensor 180 is able to sensethe temperature of microprocessor 130 when microprocessor 130 reaches athreshold level such as in the range of 70 to 100 Celsius that requiresthe cooling system to be activated in order to cool computer system 100.The cooling system is activated when temperature sensor 180 sends asignal to power management system 132 indicating that a thresholdtemperature has been reached by microprocessor 130. Power managementsystem 132 controls operating conditions of the cooling system forcomputing device 100 such as the cooling fluid pumping rate. Powermanagement system 132 may include memory or be coupled to a memorydevice. Memory may include read only memory (“ROM”), random accessmemory (“RAM”), magnetic disk storage media, optical storage media,flash memory devices, and/or other machine-readable media. Using programinstructions stored within power management system 132 or in any othersuitable location such as the chip set (not shown) of computer system100, power management system 132 controls the cooling system by thensending a signal to pump 150 to start pumping fluid from fluid container140. Once the temperature of microprocessor 130 is below the thresholdtemperature, power management system 132 sends another signal to pump150 to stop pumping fluid from fluid container 150.

Fluid sensor 190 is also coupled to fluid container 140 and to powermanagement system 132. Fluid sensor 190 is configured in such a mannerto detect when the fluid contained in fluid container 140 reaches alevel that requires fluid to be added to fluid container 140. If thefluid in fluid container 140 is low, fluid sensor 190 sends a signal topower management system 132. This indicates to power management system132 that pump 150 should stop pumping. Power management system 132 mayalso send a signal to the graphic user interface of computer system 100that the fluid is low in fluid container 140.

Tube 115 is also coupled to coupling disconnect 170 which allows a userto detach tube 115 and couple tube 115 to an externally supplied chilledfluid or a fluid that is capable of reducing heat generated frommicroprocessor 130. This externally supplied fluid is stored and pumpedby the external cooling loop inside container 200. Coupling disconnect170 may be used to either augment the existing cooling system or disablea portion of the closed loop system formed by tube 115. FIG. 3illustrates one such path of the fluid when the coupling disconnect 170is used in conjunction with externally supplied fluid stored incontainer 200.

Thereafter, tube 115 is connected to heat transfer plate 125 such as aplate-fin type liquid heat transfer plate that is located nearmicroprocessor 130 in the first part 110 of computer system 100.Plate-fin type liquid heat transfer plates utilize plates or fins thatserve as heat-transfer surfaces and a frame to support the plates orfins. Heat-transfer plates generally comprise copper, aluminum, orstainless steel, but titanium, nickel, monel, Incoloy 825, Hastelloy C,phosphor bronze and cupronickel may also be used. Heat transfer platesor fins induce turbulence in the fluids and assure more efficient heattransfer and complete flow distribution. The cooling fluid passesthrough tube 115 and into one side of the heat transfer plate 125. Asthe cooler fluid passes through heat transfer plate 125 and through aplurality of heat transfer fins 360 shown in FIGS. 6 and 7, heat isexchanged from the metal surfaces of the heat transfer plate to thecooling fluid.

After the heat is exchanged through heat transfer plate 125 whichresults in cooling microprocessor 130, the fluid in tube 115 travelsthrough the remainder of first part 110 and enters second part 120 ofcomputing device 100. The fluid follows the path of tube 115 in avertical direction relative to first part 110 of computing device 100.In the top portion of second part 120, the fluid travels in a generallyhorizontal direction and then in a downward direction of second part 120of computing device 100. The fluid then exits second part 120 and enterscoupling disconnect 170 and passes back into fluid container 140. Thecycle then repeats until microprocessor 130 is properly cooled to atemperature that is generally designated by the manufacturer of thecomputer system such as in the range of 70 to 100 Celsius.Alternatively, the fluid may be pumped in the reverse direction of thepath described above.

In yet another embodiment of the invention, a different path of thefluid flow is shown in FIG. 3. Coupling disconnect 170 is connected toan externally chilled fluid source such as container 200. The externallychilled fluid provides another route for the fluid to flow throughcomputing device 100. The fluid passes through fluid container 140 andtravels beneath or around microprocessor 130 and through heat transferplate 125. The fluid exits tube 115 returning the fluid to container 200through tube 198. FIGS. 4-5 illustrate cross-sectional views ofbi-directional tube 198 shown in FIG. 3 that allows cooling fluid to betransported to computing device 100 through a portion of tube 198connected to container 200 and the fluid that has completed its paththrough the cooling system is returned to container 200 through anotherportion of bi-directional tube 198. For example, FIG. 4 illustrates across-sectional view of bi-directional tube 198 in which cooling fluidtravels toward computing device through inner tube 117 and the fluid isreturned to container 200 for chilling through tube 118. Alternatively,FIG. 5 illustrates dual tubes 119 in tandem. One tube is for allowingchilled fluid to be transported to the computing device 100 and theother tube allows the fluid to be returned to container 200. In anotherembodiment, some other container (not shown) may be used to store thefluid that has been used to cool computing device 100.

In yet another embodiment, the fluid does not bypass heat transfer plate210. Instead, after the fluid travels beneath or around microprocessor130, the fluid exits the first part 110 and enters the second part 120of computing system 100. The fluid then travels through heat transferplate 210 of second part 120 of computing device 100. Thereafter, thefluid exits tube 115 and enters container 200 or some other container(not shown).

In another embodiment, the fluid may flow in the reverse path. Forexample, the fluid may be pumped from container 200 to couplingdisconnect 170. From coupling disconnect 170, the fluid enters tube 115and begins to travel through second part 120 of computing device 100following the path defined by tube 115. The fluid exits second part 120of computing device 100 and enters first part 110 of computing device100. The fluid travels beneath or near microprocessor 130 and thenenters fluid container 140. The fluid exits fluid container 140 and thenenters container 200. This external cooling system may be located in avariety of places such as a docking station, an alternating currentbattery charger brick, or some other suitable location.

FIGS. 6-8 show enlarged views of the first and second heat transferplates (125, 210). FIG. 6 illustrates a cross-sectional view of the heattransfer system for first heat transfer plate 125. Solder balls 310 areconnected to integrated circuit package 320 which is further coupled tointegrated circuit 330. Thermal bond line 340 acts as a conductiveadhesive between integrated circuit 330 and first heat transfer plate125. Thermal bond line 340 may include materials such as grease, epoxy,elastomeric material, graphite, or any other suitable material. Firstheat transfer plate 125 is connected to a plurality of heat sink pinfins 360.

FIG. 7 illustrates a top view of first heat transfer plate 125. The heatgenerated from integrated circuit 330 is transferred through thermalbond line 340 to first heat transfer plate 125 and heat sink pin fins360. Fluid from tube 115 enters inlet 410 and passes over first heattransfer plate 125 and into heat sink pin fins 360. The fluid has aturbulent flow through heat sink pin fins 360 which causes the fluid tohave longer contact with first heat transfer plate 125 and heat sink pinfins 360. The heat is transferred from first heat transfer plate 125 andheat sink pin fins 360 to the fluid which exits first heat transferplate 125 through outlet 420 and reenters tube 115.

FIG. 8 illustrates a top view of second heat transfer plate 210 that islocated in second part 120 of computing device 100. Second heat transferplate 210 has a large surface area that allows heat to be transferred toambient air through conduction and convection. Tube 115 is arranged tohave a plurality of passes in second part 120 of computing device 100 inorder to take advantage of the large surface area of second heattransfer plate 210. Fluid enters inlet 410 and follows the path of tube115 and exits outlet 420. In addition, air passes through air inlet 440,travels across heat transfer plate 115 and exits air outlet 450 whichalso serves to cool computer system 100.

FIG. 9 illustrates a cross-sectional view of second heat transfer plate210. A plurality of fins 430 are located perpendicular to display 444.Fins 430 are air cooled as described above which provides greater heattransfer from tube 115 and the ambient air.

FIG. 10 illustrates a flow diagram of one embodiment of the invention.At block 500, a first heat transfer plate is located near or underneathan electronic component in a first part of a computing device. At block510, at least one tube is coupled to a first heat transfer plate and asecond heat transfer plate. The tube that is connected to the firsttransfer plate may be made of one material such as plastic whereas thetube connected to the second heat transfer plate may comprise anothermaterial such as metal. Alternatively, the tube may be made of the samematerial. At block 520, fluid is circulated through the tube coupled tothe first heat transfer plate and to the second heat transfer plate. Atblock 530, heat is removed from the electronic component.

FIG. 11 illustrates a flow diagram in which chilled fluid is supplied tothe computing device. At block 600, a tube having chilled fluid iscoupled to a coupling disconnect. At block 610, the tube is located nearan electronic component such as microprocessor. At block 620, the tubeis coupled to a first heat transfer plate and a second heat transferplate. At block 630, fluid is circulated through the tube coupled to thefirst and second heat transfer plates. At block 640, heat is removedfrom the electronic component.

In the preceding detailed description, the invention is described withreference to specific embodiments thereof. It will, however, be evidentthat various modifications and changes may be made thereto withoutdeparting from the broader spirit and scope of the invention as setforth in the claims. The specification and drawings are, accordingly, tobe regarded in an illustrative rather than a restrictive sense.

What is claimed is:
 1. An apparatus, comprising: a tube to encase afluid, a first portion of the tube disposed in a base portion of amobile computing device, a second portion of the tube disposed in adisplay portion of the mobile computing device; a pump, coupled to thetube, to circulate the fluid in the tube.
 2. The apparatus of claim 1,wherein the base portion of the mobile computing device and the displayportion of the mobile computing device are coupled by a hinge.
 3. Theapparatus of claim 1, wherein the fluid comprises water.
 4. Theapparatus of claim 1, further comprising: a fluid container, coupled tothe tube, capable of storing an amount of the fluid.
 5. The apparatus ofclaim 1, wherein the fluid absorbs an amount of heat proximate to thetube at least at a part of the portion of the tube disposed in the baseportion of the mobile computing device, and wherein the fluid dissipatesan amount of heat at least at a part of the tube disposed in the displayportion of the mobile computing device.
 6. The apparatus of claim 1,wherein the tube comprises a stainless steel tube.
 7. The apparatus ofclaim 1, wherein the base portion of the mobile computing deviceincludes a keyboard.
 8. The apparatus of claim 1, wherein at least apart of the portion of the tube disposed in the base portion of themobile computing device is proximate to a heatsink, the heatsink coupledto a processor.
 9. The apparatus of claim 1, wherein at least a part ofthe portion of the tube disposed in the base portion of the mobilecomputing device is within a heatsink, the heatsink coupled to aprocessor.
 10. A mobile computing device, comprising: a base portion; adisplay portion; a tube to encase a fluid, a first portion of the tubedisposed in the base portion, a second portion of the tube disposed inthe display portion, wherein the base portion and the display portionare coupled by a hinge; a pump, coupled to the tube, to circulate thefluid in the tube.
 11. The mobile computing device of claim 10, whereinthe fluid comprises water.
 12. The mobile computing device of claim 10,further comprising: a fluid container, coupled to the tube, capable ofstoring an amount of the fluid.
 13. The mobile computing device of claim10, wherein the fluid absorbs an amount of heat proximate to the tube atleast at a part of the portion of the tube disposed in the base portionof the mobile computing device, and wherein the fluid dissipates anamount of heat at least at a part of the tube disposed in the displayportion of the mobile computing device.
 14. The mobile computing deviceof claim 10, wherein the tube comprises a stainless steel tube.
 15. Themobile computing device of claim 10, wherein the base portion of themobile computing device includes a keyboard.
 16. The mobile computingdevice of claim 10, wherein at least a part of the portion of the tubedisposed in the base portion of the mobile computing device is proximateto a heatsink, the heatsink coupled to a processor.
 17. The mobilecomputing device of claim 10, wherein at least a part of the portion ofthe tube disposed in the base portion of the mobile computing device iswithin a heatsink, the heatsink coupled to a processor.